This invention relates to apparatus for administering intravenous drugs to a patient, in particular drugs supplied in powdery form.
When administering intravenously to a patient a drug initially supplied in powdery form, where the individual particles are either loose or compacted into cake form, such as a cytotoxic agent for treating cancer, a standard procedure is currently adopted. This procedure involves providing a sealed container holding the powdery drug and injecting into the bottle, by way of a standard syringe and hypodermic needle, a volume of intravenously-acceptable liquid in which the drug will dissolve. The container is then shaken until the drug is dissolved and a solution is formed.
A volume of air equal to that of the previously injected liquid is then drawn into the syringe and is injected into the container to equalise the pressures in the syringe and the container, and the desired volume of liquid medicament is drawn into the syringe.
Said syringe is then removed from the container and the drug is injected into the patient.
Such a procedure has a number of disadvantages, the administrator of the drug being particularly prone to possible exposure to the drug. For example, the needle of the syringe may accidentally be removed from the body of the syringe during charging of said syringe; the needle may be accidentally removed from the container during said charging; the supposedly fluid-tight rubber stopper on the container may develop a leak after removal therefrom of the needle.
In all such cases there is a possibility of the drug contacting or entering the doctor or nurse administering the drug--whereas cytotoxic drugs can successfully treat a patient with cancer, most of them are known to be cancer-producing agents as well. Thus it will be appreciated that the problems are of some significance.
Furthermore, many cytotoxic agents and other drugs are photosensitive in that any, or extended exposure to light causes degradation of the drugs, rendering them substantially less effective and some of them more toxic, e.g. Dacarbazine.
When administering such photosensitive drugs by means of the above-detailed procedure, it has become standard practice to wrap the syringe in silver foil or dark paper to eliminate light and to inject the drug into a patient in a dark room. Clearly such a procedure leaves the doctor or nurse particularly prone to accidental exposure to the drug, and the drug open to possible contamination by hospital ward bacteria.
As is always the case when administering drugs to a patient, it is advisable, if not essential, that all the apparatus used is sterile and that no bacteria or the like is contained within the drug itself. This is particularly important as regards patients being treated with cytotoxic agents as such treatment reduces substantially the patient's general immunity and the presence of any bacteria in the drug can have drastic effects.
In the above-detailed established procedure for injecting drugs using a standard syringe and hypodermic needle, it will be appreciated that it is necessary to bubble air through the solution to equalise the pressures in the syringe and container. If, as is common practice, the air used is from a hospital ward atmosphere, the problem of bacteria is particularly prevalent. This is because such atmospheres carry resistant strains of bacteria and therefore are more likely to cause problems on immunodepressed patients.